Abstract
Small interfering RNAs (siRNAs) present a strong therapeutic potential because of their ability to inhibit the expression of any desired protein. However, siRNAs show a very weak propensity to cross the plasma membrane on their own. We recently developed a new family of amphipathic peptides called WRAP (W- and R-rich Amphipathic Peptides) able to form stable peptide-based nanoparticles (PBNs) once incubated with a given ratio of siRNA [Konate 2019]. The PBN efficiency for the cellular delivery of therapeutic molecules has been several times highlighted during the recent years with an impressive number of examples [Jafari 2015, Lehto 2016] including those reported in our group [Konate 2016, Vaissière 2017, Konate 2019].For in vivo application, we have grafted to the WRAP nanoparticles a PEG moiety to protect the nanoparticle in the blood circulation and to increase biodistribution. Indeed, we observed that WRAP nanoparticles were more stable in the presence of higher salt concentrations. More importantly, this grafting allowed us to silence the green fluorescence protein (GFP) overexpressed in HEK cells in the same way as the naked nanoparticles. Encouraged by these results, we conduct a proof of concept study revealing that GFP silencing in zebrafish embryos overexpressing GFP in vascular endothelial cells is possible by simply bathing the embryos in the nanoparticle solution.In parallel, a mitochondrial-targeting sequence (MTS) has been incorporated on the WRAP nanoparticles, to confer on them a targeting ability. These nanoparticles containing the plasmid for a mitochondrial protein ND1 were characterized in terms of pDNA complexation capacity, morphology, size, surface charge, and cytotoxic profile. Furthermore, in vitro studies illustrated the mitochondrial targeting ability of MTS-WRAP:pDNA complexes [Faria 2021].Our results highlighted the potential use of this class of WRAP nanoparticles thus allowing siRNA delivery in a wide variety of cell types and applications.